Optical imaging of diffuse medium

ABSTRACT

A display pixel array is illuminated by infrared light in a frequency band. An infrared holographic imaging signal is generated by driving a holographic pattern onto the display pixel array. An image of an exit signal of the holographic infrared imaging signal is captured with an image pixel array. The image pixel array is configured to capture the infrared light and reject light outside the frequency band.

TECHNICAL FIELD

This disclosure relates generally to imaging, and in particular but notexclusively to medical imaging using infrared light.

BACKGROUND INFORMATION

Rising healthcare costs put economic pressure on families and businessesin addition to constraining access to healthcare to those that canafford the increased cost. Some modes of medical imaging are large costdrivers in medical expenses since the systems and devices thatfacilitate the medical imaging are valued in the millions of dollars. Asa result of the high price of some medical imaging systems, alternativetesting and/or less accurate modes of medical imaging arestandard-of-care, even though the more expensive medical imaging systemis a better diagnostic tool. In developing nations, the high price ofmedical imaging systems such as MRIs (Magnetic Resonance Imaging) limitsaccess to medical imaging because of both price and physical accesssince the sparse geographical distribution of medical imaging systemsalso imposes a travel barrier for those that would benefit from them.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1 illustrates an example imaging system that includes a display andan image pixel array, in accordance with an embodiment of thedisclosure.

FIG. 2 illustrates an example imaging system that includes a display andan image pixel array, in accordance with an embodiment of thedisclosure.

FIG. 3 illustrates example placement of components of an imaging systemin relationship to a human head, in accordance with an embodiment of thedisclosure.

FIGS. 4A and 4B illustrate example form-factor implementations of awearable imaging system, in accordance with an embodiment of thedisclosure.

FIG. 5 illustrates an example configuration of a flexible wearableimaging system, in accordance with an embodiment of the disclosure.

FIG. 6 illustrates a networked system in communication with an examplewearable imaging system for being worn on or about a head, in accordancewith an embodiment of the disclosure.

FIGS. 7A-7C illustrate example embodiments of a directional ultrasonicemitter, in accordance with an embodiment of the disclosure.

FIGS. 8A-8B illustrate example embodiments of displays for generatingholographic infrared imaging signals, in accordance with an embodimentof the disclosure.

FIG. 9 illustrates an example process of linking a holographic patternto a location in a diffuse medium, in accordance with an embodiment ofthe disclosure.

FIG. 10 illustrates an example imaging system that includes a displayand an image pixel array, in accordance with an embodiment of thedisclosure.

FIG. 11 illustrates an example process of linking a holographic patternto a location in a diffuse medium, in accordance with an embodiment ofthe disclosure.

DETAILED DESCRIPTION

Embodiments of a system, device, and method for optical imaging of adiffuse medium is described herein. In the following description,numerous specific details are set forth to provide a thoroughunderstanding of the embodiments. One skilled in the relevant art willrecognize, however, that the techniques described herein can bepracticed without one or more of the specific details, or with othermethods, components, materials, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring certain aspects.

The content of this disclosure may be applied to medical imaging as wellas other fields. Human tissue is translucent to infrared light, althoughdifferent parts of the human body (e.g. skin, blood, bone) exhibitdifferent absorption coefficients. Researchers have attempted to use theproperties of infrared light for medical imaging purposes, but size andcost constraints have been prohibitive for wide-scale adoption.Illuminating tissue with near-infrared light for imaging purposes issometimes referred to as Diffuse Optical Tomography. In one DiffuseOptical Tomography technique, time-of-flight (TOF) imaging cantheoretically be employed by measuring the time it takes for “ballistic”photons (those photons that are not scattered) to pass through tissue.Since the ballistic photons reach the sensor the fastest, they are theleast impeded (have the shortest optical path) and thus some conclusioncan be drawn to create an image of the tissue that is illuminated byinfrared light. However, TOF imaging generally requires specialtyhardware (e.g. picosecond pulsed lasers and single photon detectors) tofacilitate ultrafast shutters on sensors that are able to image at thespeed of light and the systems are overall very expensive and bulky. TOFimaging also requires an input of approximately 10-100 fold (or more)light intensity into the body than is used at the detector; thusefficacy and power limitations as well as safety limits on inputintensity limit TOF imaging resolution and utility. In contrast to TOFimaging, embodiments of this disclosure utilize a holographic beam todirect infrared light to a voxel of a diffuse medium (e.g. a brain ortissue). A light detector (e.g. image pixel array) measures an exitsignal of the holographic beam. The exit signal is the infrared light ofthe holographic beam that is reflected from and/or transmitted throughthe voxel. The light detector may include a pixel array that measuresthe amplitude and determines the phase of the exit signal that isincident on the pixels. By capturing an image of the exit signal changes(e.g. oxygen depletion in red blood cells, scattering changes induced bypotential differences in an activated neuron, fluorescent contrastagents and other optical changes) at a voxel or group of voxels in thediffuse medium, changes to that voxel or group of voxels can be recordedover time as the absorption, phase of scattering of the holographic beamvaries with the changes in the tissues. Multiple voxels can be imaged bychanging a holographic pattern on a display to steer the holographicbeam toward the different voxels or groups of voxels. By raster scanningthrough many voxels (and recording the exit signals), a threedimensional image of the diffuse medium can be constructed.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

Throughout this specification, several terms of art are used. Theseterms are to take on their ordinary meaning in the art from which theycome, unless specifically defined herein or the context of their usewould clearly suggest otherwise.

FIG. 1 illustrates an example imaging system 100, in accordance with anembodiment of the disclosure. Imaging system 100 includes processinglogic 101, a display 110, and an image pixel array 170. In FIG. 1,imaging system 100 also includes a directional ultrasonic emitter 115coupled to be driven by processing logic 101. In FIG. 1, display 110includes an infrared emitter 105, an infrared director 103, and adisplay pixel array 113. Display pixel array 113 may be an LCD (liquidcrystal display), for example. The LCD display may be an active-matrix(using thin-film-transistors) or a passive matrix LCD. In oneembodiment, the LCD display has pixels that are less than 7 microns.

In one embodiment, display 110 is a holographic display. For thepurposes of this disclosure, a holographic display includes a displaywhere each pixel of the display can independently modulate the phase andintensity of light that illuminates the pixel. The array of pixels mayutilize a transmissive architecture (e.g. modulating transmissionthrough liquid crystal) or a reflective architecture (e.g. LiquidCrystal on Silicon).

Processing logic 101 may include a processor, microprocessor, cluster ofprocessing cores, FPGA (field programmable gate array), and/or othersuitable combination of logic hardware. Although not illustrated, system100 may include a wireless transceiver coupled to processing logic 101.The wireless transceiver is configured to wirelessly send and receivedata. The wireless transceiver may utilize any suitable wirelessprotocol such as cellular, WiFi, BlueTooth™, or otherwise.

In FIG. 1, display pixel array 113 is illustrated as a transmissive LCDthat is illuminated by infrared wavefront 107. In the illustratedembodiment, infrared (IR) emitter 105 is coupled to be driven by outputX3 of processing logic 101. When processing logic 101 turns on IRemitter 105, infrared light propagates into IR director 103. IR director103 may be a light guide plate similar to those found in conventionaledge lit LCDs. IR director 103 may be a slim prism utilizing TIR (totalinternal reflection). IR director 103 redirects the infrared lighttoward display pixel array 113. IR director 103 may include a sawtoothgrating to redirect the infrared light toward IR display 113. IR emitter105 is an infrared laser diode that emits monochromatic infrared light,in one embodiment. Monochromatic light may be defined as light within a4 nm frequency band, for example. IR emitter 105 in one embodiment ispulsed, and in another embodiment is CW (continuous wave). The infraredlight that IR emitter 105 emits may be centered around a frequency inthe 700-1000 nm range. In one embodiment, the infrared light that IRemitter 105 emits may be centered around a frequency in the 1600-1700 nmrange. In one example, emitter 105 generates monochromatic lightcentered around 850 nm.

Steerable infrared beams can be generated by display 110 by drivingdifferent holographic patterns onto display 110. Each differentholographic pattern can steer (focus) the infrared light in a differentdirection. The directional nature of the infrared beam is influenced bythe constructive and destructive interference of the infrared lightemitted from the pixels of display 110. As an example, a holographicpattern that includes different “slits” at different locations cangenerate different infrared beams. The “slits” can be generated bydriving all the pixels in the display pixel array 113 to “black” (nottransmissive) except for the pixels where the “slits” are located aredriven to be “white” (transmissive) to let the infrared light propagatethrough. In one embodiment, the pixel size of display 110 approximatesthe wavelength of light illuminating the display. The pixel size may be1 micron, although in some embodiments pixels sized up to 10 times thewavelength of light can be used. In one example, if IR emitter 105 is an850 nm laser diode, the pixel size of display 110 may be 850 nm. Thepixel size influences the angular spread of a hologram since the angularspread is given by the Grating Equation:sin(θ)=mλ/d  (Equation 1)where θ is the angular spread of light, m is an integer number and theorder of diffraction, and d is the distance of two pixels (a period).Hence, smaller pixel size generally yields more design freedom forgenerating holographic beams, although pixels sizes that are greaterthan the wavelength of light can also be used to generate holographicimaging signals. Display pixel array 113 may include square pixels(rather than the rectangular pixels in conventional RGB LCDs) so thatthe Grating Equation is applicable in both the x and y dimensions of thepixel array.

In FIG. 1, system 100 includes an ultrasonic emitter 115. Ultrasonicemitter 115 is configured to focus an ultrasonic signal to a point inthree-dimensional space. In the medical context, the ultrasonic emitter115 is configured to focus an ultrasonic signal to a voxel within thehuman body. The voxel may be within the brain, abdomen, or uterus, forexample. Focusing an ultrasonic signal to a given voxel of tissuecreates a (temporary) localized compression zone at the voxel. In turn,the localized compression zone affects the propagation of infrared lightthrough the localized compression zone. In particular, the phase ofinfrared light is modulated as a result of the localized compression ofthe tissue. As will be discussed in more detail below, the change ofphase at the localized compression zone can be measured in a way thatassists imaging tissue, or other diffuse mediums. Processing logic 101is coupled to drive directional ultrasonic emitter 115 to focusultrasonic signal 117 to different locations in three-dimensional spacevia output X1, in the illustrated embodiment. The directional ultrasonicemitter 115 can be driven to focus an ultrasonic signal to voxel 133 inthree-dimensional diffuse medium 130, for example.

Imaging module 160 is positioned to image exit signal 143, in FIG. 1. Asinfrared holographic imaging signal 123 propagates through diffusemedium 130 and at least a portion of it propagates through voxel 133 andexits diffuse medium 130 as exit signal 143. Exit signal 143 is atransmission signal in that imaging module 160 is imaging thetransmission of infrared holographic imaging signal 123 through voxel133. Reflective transmission signals (the reflection of holographicimaging signal 123 from voxel 133) may be measured in other embodiments.

Imaging module 160 includes IR emitter 155, IR director 153, and imagepixel array 170. IR emitter 155 is coupled to receive an activationsignal from processing logic 101 by way of output X4. IR emitter 155emits an infrared light that shares the same characteristics as theinfrared light emitted by IR emitter 105. IR emitter 105 and IR emitter155 may be identical emitters. In one embodiment, instead of havingseparate emitters for IR emitter 105 and IR emitter 155, fiber opticlines direct infrared light from a shared IR emitter to IR director 103and IR director 153. In this embodiment, when processing logic 101activates the IR emitter, the infrared light emitted by the IR emittertravels through the fiber optics to illuminate both IR director 103 and153. IR director 153 redirects the IR light emitted by IR emitter 155toward image pixel array 170 as reference wavefront 157. IR emitter 155paired with IR director 153 is one example of a reference wavefrontgenerator for generating reference wavefront 157. IR director 153 may bemade from a transparent plastic or glass such that IR director 153 istransparent to (or distorts in a known way) exit signal 143 thatencounters IR director 153. IR director 153 may include a diffractivegrating that is tuned to redirect the infrared light from IR emitter 153toward image pixel array 170. The diffractive grating can be embeddedwithin a transparent material of the IR director 153 so that itredirects a specific wavelength of IR light received from a particularangle (e.g. same angle as the IR emitter 155 is positioned) but isotherwise transparent to (or distorts in a known way) exit signal 143since exit signal 143 is not incident upon the diffractive grating atthe same angle as the IR light emitted by IR emitter 155. In oneembodiment, IR director 153 includes a light guide plate as used in mostliquid crystal display systems.

In the illustrated embodiment, an infrared filter 173 is disposedbetween IR director 153 and image pixel array 170. Infrared filter 173passes the wavelength of infrared light emitted by IR emitters 105 andIR emitter 155 and rejects other light wavelengths that image pixelarray 170 is sensitive to. Infrared filter 173 may be a bandpass filterwith a bandwidth of four nanometers centered around the frequency ofmonochromatic IR light emitted by emitters 105 and 155. Although notillustrated, a focusing lens may be disposed between image pixel array170 and IR director 153. The focusing lens may be configured to focusreference wavefront 157 and exit signal 143 such that the interferencepatterns of reference wavefront 157 and exit signal 143 are well focusedon pixels of image pixel array 170 such that there is sufficientresolution for analysis of the interference patterns.

Image pixel array 170 may be implemented with an a-Si (amorphousSilicon) thin film transistors, in some embodiments or a CMOS(Complimentary Metal-Oxide-Semiconductor) image sensor, in someembodiments. Image pixel array 170 can be a commercially available imagesensor, or optimized for detecting differences in signal rather than themaximum dynamic range of the signal, as for example as shown in by K. P.Hofmann and D. Emeis “Differential Light Detector” Rev. Sci Instrum 50,249 1979, or in the case of detecting the change of holographic fringepatterns use processing logic 101 suited for detecting shifts inpatterns.

The pixel resolution of image pixel array 170 may vary depending on theapplication. In one embodiment, the image pixel array 170 is 1920 pixelsby 1080 pixels. In one embodiment, the image pixel array is 40Megapixels or more. Some of the processing can be done in the imagepixel array itself to enable lower bandwidth connections off chip. Imagepixel array 170 can capture an infrared image of exit signal 143 bymeasuring the image charge generated in each pixel during a givenintegration period that is determined by an electronic shutter. Theelectronic shutter may be a global shutter (where each pixel measuresthe incident light during a same time period) rather than a rollingshutter. The electronic shutter can be actuated by processing logic 101via input/output X5. Input/output X5 may include digital input/outputlines as well as a data bus. Image pixel array 170 is communicativelycoupled to processing logic 101 to send the captured infrared images toprocessing logic 101 for further processing. Image pixel array 170 mayinclude a local (on-board) digital signal processor (DSP), in someembodiments, and processing logic 101 may receive the captured infraredimages from the DSP.

In addition to capturing the amplitude of incident infrared light, thephase of incident infrared light can be determined from recordinginterference patterns using imaging module 160. The amplitude(intensity) of incident infrared light is measured by simply reading outthe image charge accumulated in each photosensor (e.g. photodiode) ofthe pixels of image pixel array 170. The phase of light from exit signal143 can also be measured by activating IR emitter 155 during theintegration period of pixels of image pixel array 170. Since exit signal143 is the same monochromatic wavelength as reference wavefront 157, thelight interference of the exit signal 143 and the reference wavefront157 indicates the phase of the infrared light of exit signal 143. Theinterference patterns created by the interference of exit signal 143 andreference wavefront 157 will be recorded by the image pixel array 170.The interference patterns can be analyzed to determine the phase of exitsignal 143. The phase of and/or amplitude of different exit signals 143can be analyzed to determine a suitable holographic pattern to image agiven voxel (e.g. voxel 133).

One example process of linking a holographic pattern for driving ontodisplay 110 to a given voxel utilizes directional ultrasonic emitter115. To start this example process of linking a preferred holographicpattern (for driving onto display 110) to a given voxel in a diffusemedium, image pixel array 170 may initiate two image captures when aninitial holographic pattern is driven onto display 110. The first imagecapture measures the amplitude of exit signal 143 by measuring theinfrared light from exit signal 143 interfering with the light fromreference wavefront 157 while the directional ultrasonic emitter 115 ofFIG. 1 is off and thus captures the exit signal 143 with no phase changeinduced in voxel 133 by ultrasonic emitter 115. The phase of exit signal143 can also be determined by analyzing the amplitude of different pixelgroups that show interference patterns of exit signal 143 interferingwith reference wavefront 157. The second image capture measures theinterference of reference wavefront 157 with exit signal 143 whendirectional ultrasonic emitter 115 is activated and focused on voxel133. As with the first image capture, both the amplitude and phase ofexit signal 143 can be determined from the second image capture. Sincethe ultrasonic signal 117 locally compresses voxel 133 and induces aphase change of light propagating through the voxel 133, the first imagecapture and the second image capture will be different when theholographic pattern that is driven onto display 110 propagates throughvoxel 133. When the difference between the first image capture and thesecond image capture is maximized (to an acceptable level), theholographic pattern driven onto display 110 can be said to best focusedon voxel 133 and is the preferred holographic pattern and thus linked tothe voxel. Therefore, after the difference between the first and secondimage capture with the initial holographic pattern driven onto display110 is calculated, the initial holographic pattern may be iterated todetermine if a second holographic pattern driven on display 110generates an even greater difference (measured by amplitude and/orphase) between a first and second image capture. Signal 123 is alteredby driving a different holographic pattern on display 110, via forexample simulated annealing, to maximize the difference between thefirst image capture and the second image capture. The holographicpattern may be iterated many times while seeking the largest changebetween the first and second image capture. This technique is used tocreate a dictionary (i.e. lookup table) of holographic patterns(corresponding to input signal 123) to map to focus the lightsequentially to each and every voxel and to enable raster scanning ofthe volume, one voxel at a time. The first and second image capture mayoccur successively, one immediately after the other, to limit any changein exit signal 143 between image captures due to changes in diffusemedium 130.

In system 180 illustrated in FIG. 10, imaging module 160 is positionedto image exit signal 143, similarly to in FIG. 1. However, system 180 ofFIG. 10 does not include a directional ultrasonic emitter 115. Infraredholographic imaging signal 123 still propagates through diffuse medium130 and exits diffuse medium 130 as exit signal 143. In FIG. 10,infrared holographic imaging signal 123 is depicted as light that isscattered by diffuse medium 130 while still propagating through thevoxel(s) of interest. The scattered light paths of both signal 123 and143 illustrated in FIG. 10 may be more realistic than the “clean” beamsof FIGS. 1 and 2, illustrated for explanation purposes.

A process for linking a preferred holographic pattern (for driving ontodisplay 110) to a voxel or a given set of voxels is different for system180 since system 180 does not include directional ultrasonic emitter115. For system 180, to start an example process of linking a preferredholographic pattern to a given set of voxels (two of this set aredepicted as voxel 199 and voxel 198 in a diffuse medium 130 in FIG. 10),image pixel array 170 may initiate two image captures when an initialholographic pattern is driven onto display 110. The first image capturemeasures the amplitude of exit signal 143 by measuring the infraredlight from exit signal 143 interfering with the light from referencewavefront 157 prior to application or presentation of stimulus 197 andthus captures the exit signal 143. The exit signal 143 may be analyzedfor its amplitude alone or by signal 143 interfering with referencewavefront 157. The second image capture measures the effect of stimulus197. The stimulus 197 is an internal change to a voxel or weighted groupof voxels such that light is absorbed, phase retarded or scattered in adifferent way by that single voxel or group of voxels. In the brain sucha change could be created by showing an image to a subject, playing somemusic to a subject, a request to a subject to think about something, orsimply a wait for a change (internal bleeding, tumor growth, etc.) andother examples. Changes to blood that change the optical signal can bedetected (deoxygenated blood absorbs light differently than oxygenatedblood), blood volume itself can be detected and changes in itsvasculature and flow, lipids, water, fat, melanin, and changes inscattering as can be seen in the direct firing pattern of neurons.Activity of neurons is characterized by ion and water fluxes across theneuron membrane inducing a change in membrane potential which can beseen by a change in light scattering as a function of neuron activity onthe millisecond time scale. Fluorescent chemicals, nanoparticles placedvia injection, injection or other means can also be used as beacons,including 2-photon systems and other methods where the wavelength oflight is shifted at the voxel, area of interest or areas of interest.Many stimuli can impart optical changes inside the diffuse medium, thesechanges themselves, caused by the stimuli can be used as the beacons totune the holographic image to focus on the region of change. The systemcan learn over time, akin to the way speech to text systems train onuser's speech and grow continually better over time leveraging the dataset and other implied and inferred data. Other existing anatomical data,or map data can be added to this model to extract more information andinfer more information about the sites of interest. This work leveragestechniques in machine learning, neural nets, deep learning, artificialintelligence and so forth.

With the stimulus present exit signal 143, as with the first imagecapture, both the amplitude and phase of exit signal 143 can bedetermined from the second image capture. With a stimulus 197applied/presented for the second image capture, the first image captureand the second image capture will be different when the holographicpattern that is driven onto display 110 propagates through the multiplevoxels affected by the stimulus 197. When the difference between thefirst image capture and the second image capture is maximized (to anacceptable level), the holographic pattern driven onto display 110 canbe said to best represent delivering a measurement signal of thestimulus 197 and is the preferred holographic pattern and thus linked toa given stimulus. Therefore, after the difference between the first andsecond image capture with the initial holographic pattern driven ontodisplay 110 is calculated, the initial holographic pattern may beiterated to determine if a second holographic pattern driven on display110 generates an even greater difference (measured by amplitude and/orphase) between a first and second image capture. Signal 123 is alteredby driving a different holographic pattern on display 110, via forexample simulated annealing, to maximize the difference between thefirst image capture and the second image capture. The holographicpattern may be iterated many times while seeking the largest changebetween the first and second image capture. This technique is used tocreate a dictionary (i.e. lookup table) of holographic patterns(corresponding to input signal 123) to map to focus the lightsequentially to each and every stimulus 197 and scanning of variousstimuli.

FIGS. 7A-7C illustrate example configurations of ultrasonic emitter 115.In FIG. 7A, directional ultrasonic emitter 115 includes a point sourceultrasonic emitter 703 and an electronically controlled membrane 713.Point source ultrasonic emitter 703 is directed toward an electronicallycontrolled membrane 713 that changes shape according to electronic inputfrom processing logic 101. Changing the lensing shape of the membrane713 electronically causes the ultrasonic signal 707 to be reflected andfocused as beam 717 to the area of interest 723 in a diffuse medium 730.In one embodiment, the membrane includes polyvinylidene fluoride (PVDF).

In the embodiment illustrated in FIG. 7B, directional ultrasonic emitter115 includes a piezo-membrane 733 that emits focused ultrasonic beam 737to area of interest 747. Piezo-membrane 733 is a membrane having anarray of regions and different electronic signals that drive thedifferent regions. By selectively activating the different regions ofthe piezo-membrane 733, ultrasonic beam 737 can be focused on differentpoints of interest 747 in diffuse medium 730. Piezo-membrane 733 mayinclude polyvinylidene fluoride (PVDF).

FIG. 7C illustrates an additional embodiment of directional ultrasonicemitter 115. In FIG. 7C, the directional ultrasonic emitter includes twoultrasonic emitters. The first ultrasonic emitter includes point source703A and moveable lens 753A. The second ultrasonic emitter includespoint source 703B and moveable lens 753B. The first and secondultrasonic emitters are spaced apart from each other. The firstultrasonic emitter steers moveable lens 753A to direct an ultrasonicbeam 757A with little divergence to the point of interest 763. Beam 757Apropagates through point of interest 763, but is not focused on point ofinterest 763. The second ultrasonic emitter steers moveable lens 753B todirect an ultrasonic beam 757B with little divergence to the point ofinterest 763. Beam 757B propagates through point of interest 763, but isnot focused on point of interest 763. The intersection of beams 757A and757B create a local compression zone at point of interest 763.

The directional ultrasonic emitter 115 can be optionally used with IRdisplay 113 to create a scanning look up table that links voxels inthree-dimensional diffuse medium 130 with holographic patterns that canbe driven onto IR display 113. This can also be achieved without the useof the directional ultrasonic emitter 115 as a beacon but insteadthrough the use of other stimuli as described in [0033] and [0034].

FIGS. 8A-B illustrates an example side view of example pixels of adisplay pixel array that can be used as display pixel array 113. Displaypixel array 113 may include amplitude modulation architecture 810 or aphase modulator architecture 820 or both. Amplitude modulator 810functions similarly to conventional LCDs (modulating amplitude byadjusting voltage across liquid crystal pixel to rotate polarized light)except that the polarizers found in conventional LCDs are replaced withpolarizers configured to polarize IR wavefront 107 and the liquidcrystals are tuned to modulate infrared light. Amplitude modulator 810can be solely used to modulate the amplitude of the signal and createthe holographic wavefront 123 by creating diffractive slits for example.Phase modulator system 820 enables higher light throughput thanmodulator 810 by creating the same holographic wavefront 123 with betterefficacy. Example light rays 831 and 836 may be part of infraredwavefront 107. Light ray 831 encounters pixel 811 and the amplitude ofray 831 is modulated to the amplitude of light ray 832. Similarly, lightray 836 encounters pixel 812 and the amplitude of ray 836 is modulatedto the amplitude of light ray 837.

Alternatively, light ray 831 encounters pixel 821 and the phase of lightray 831 is modulated by pixel 821. Pixel 821 includes liquid crystals888 disposed between two electrodes (e.g. indium tin oxide). A voltageacross the electrodes changes the alignment of the liquid crystals 888and the refractive index of the pixel 821 is changed according to thealignment of the liquid crystals 888. Thus, modulating the refractiveindex shortens or lengthens the optical path through the pixel 821,which changes the phase of the light rays 833 that exits pixel 821. Inone embodiment, pixel 821 is configured so that applying a minimumvoltage (e.g. 0V) across the electrodes of pixel 821 causes light ray831 to not be phase shifted while applying a maximum voltage across theelectrodes causes light ray 831 to be phase shifted 359°. Thus, applyingvoltages across the electrodes between the minimum and maximum voltagesgive full grey-scale control of phase shifting light ray 831 between 0°(zero radians) and 359° (almost 2π radians). To achieve this range, theoptical path length of light ray 831 from the minimum to the maximumrefractive index will need to differ by almost one full wavelength ofthe light (to achieve a phase shift of 359°). In one embodiment, theoptical path length difference from the minimum refractive index is 850nm to correspond with an 850 nm laser diode that generates infraredwavefront 107. To accommodate the thickness required to change theoptical path length by almost a full wavelength, the thickness of phasemodulator stage 820 may be thicker than a conventional LCD.

The illustrated embodiment of FIG. 8A shows that different modulationcontrols (e.g. voltages across the liquid crystal) are being applied topixels 811 and 812 since the amplitude of light ray 837 exiting pixel812 is smaller than the amplitude of light ray 832 exiting pixel 811.The illustrated embodiment of FIG. 8B shows that the phase of light ray838 is adjusted 1π compared to the phase of light ray 833. As explainedabove, the phase of the light rays that propagate through pixels ofphase modulator stage 820 can be modulated by adjusting the alignment ofliquid crystals 888 to change the refractive index of the pixels in FIG.8B. As illustrated, the alignment of the liquid crystals 888 in pixels821 and 822 is different.

To generate a composite image of diffuse medium 130, multiple voxels ofdiffuse medium 130 can be imaged by imaging system 100 of FIG. 1. Priorto imaging each voxel, a focusing procedure may be performed todetermine a suitable holographic pattern to image that voxel. In FIG. 1,three-dimensional diffusing medium 130 has an x dimension, a ydimension, and a z dimension (in to the page). The focusing proceduremay start at a voxel having a coordinate of 1, 1, 1 and finish at avoxel having a coordinate of q, r, s, where q, r, and s are the numberof voxels in each dimension x, y, and, z, respectively. The dimension ofeach voxel can be any dimension. In one embodiment, each voxel is 1 cmcubed. In on embodiment, each voxel is 1 mm cubed. Smaller voxels arepossible.

In one example focusing procedure, display 110 generates a first probinginfrared holographic imaging signal 123 by driving a first probingholographic pattern onto display 110. Imaging module 160 captures exitsignal 143 in a first calibration infrared image. At a different time,directional ultrasonic emitter 115 is focused on a first voxel (e.g. 1,1, 1) and imaging module 160 captures exit signal 143 again in a secondcalibration infrared image. The phase and/or amplitude differencebetween the first calibration infrared image and the second calibrationinfrared image is determined. As described above, the phase of the lightfrom exit signal 143 may be determined by analyzing the interferencepatterns that are recorded in difference pixel groups of the calibrationimages. The amplitude of exit signals 143 can be determined simply fromthe image charge readings of each pixel. The determination of the phaseand/or amplitude difference may be made by processing logic 101 andwritten to a memory on-board processing logic 101 or an auxiliary memorycoupled to processing logic 101 (not illustrated). A difference value isthen linked to the first probing holographic pattern.

Display 110 generates a plurality of probing infrared holographicimaging signals 123 (by driving different probing holographic patternsonto display 110) and records the amplitude and/or phase difference ofexit signal 143 for each probing infrared holographic imaging signalbetween when the directional ultrasonic emitter 115 is and is notfocused on the voxel of interest. In one example, fifty probing infraredholographic imaging signals are generated by fifty different probingholographic patterns being driven onto display 110. The fifty differentholographic patterns may be random holographic patterns or may be fiftypre-determined holographic patterns that generate beam shapes that makegood searching beams that would be well distributed throughout thediffuse medium. After the amplitude and/or phase difference for eachprobing infrared holographic imaging signal is recorded, a probingholographic pattern that yielded the largest amplitude and/or phasedifference in exit signal 143 is selected. A new fifty probing infraredholography imaging signals are generated based on the selection anditeratively an optimum holographic imaging signal for a certain voxel isdetermined. As discussed above, focusing an ultrasonic signal on a voxelcreates a local compression zone that alters the phase of infrared lightpropagating through the local compression zone. Altering the phase atthe voxel will impact the phase of infrared light propagating throughthe voxel. Changing the phase at the voxel can also impact the amplitudeof infrared light received by imaging module 160 since altering thephase at voxel 133 may cause infrared light to scatter differently.Thus, the selected probing holographic pattern that generated thelargest phase difference (and/or amplitude difference) in exit signal143 can be assumed to have best directed light to image pixel array 170via the voxel of interest.

50 years ago in 1966 the Optical Society of American published anarticle entitled “Holographic Imagery through diffusing media” in theJournal of the Optical Society of America 56, 4 pg 523 authored byEmmett Leith and Juris Upatnieks. In the same years Joe Goodman et. alauthored a paper published by the American Physical Society entitled“Wavefront-reconstruction imaging through random media” Applied PhysicsLetters, 8, 311-312 (1966). This work was re-popularized by the OpticalSociety of America when it published on Aug. 15, 2007 in articleentitled “Focusing coherent light through opaque strongly scatteringmedia.” In this article and the aforementioned articles in thisparagraph, the authors describe shaping a wavefront in order to focusthe wavefront on a pre-defined target even as the shaped wavefrontencounters a scattering medium on its path to the pre-defined target.

Although the contexts are different, infrared holographic imaging signal123 can be shaped to “focus” on imaging module 160 even though itencounters a diffuse medium 130. The optical path from display 110 toimaging module 160 via voxel 133 is analogous to the “scattering sample”described by the authors of “Focusing coherent light through opaquestrongly scattering media.” The focusing procedure described in thisdisclosure is the process of shaping the holographic imaging signaldisplayed by display 110 to focus the holographic imaging signal onimaging module 160 while also propagating through a specific voxel (e.g.voxel 133).

Determining the selected probing holographic pattern that generates thelargest phase difference in exit signal 143 may be a first stage of thefocusing procedure for a given voxel. In one embodiment, a second stageof the focusing procedure includes a Simulated Annealing (SA) algorithmthat includes iterating on the selected probing holographic pattern togenerate a fine-tuned holographic pattern that generates an even greaterphase change in exit signal 143 (the larger phase change indicating evenmore infrared light being focused on imaging module 160 via voxel 133)than the selected probing holographic pattern. In another embodiment,the second stage focusing procedure (using Simulated Annealing) can beused standalone without the first stage.

The selected probing holographic pattern for the voxel, or group ofvoxels is linked to the voxel or group of voxels if only the first stageof the focusing procedure is implemented. The fine-tuned holographicpattern is linked to the voxel or group of voxels if the second stage ofthe focusing procedure is implemented. The linked holographic patternmay be stored in a lookup table. The focusing procedure is repeated foreach voxel of interest in diffusing medium 130. Hence, each voxel islinked to a preferred holographic pattern for that voxel that generatesan infrared holographic imaging signal that is focused on the particularvoxel and then can be measured as exit signal 143 by imaging module 160.Through an iterative approach, the focusing of the imaging signal 123 toa voxel or group of voxels improves over time.

Processing logic 101 has access to the lookup table, and thus, apreferred holographic pattern is linked to each voxel in diffusingmedium 130. Then, to image diffusing medium 130, the preferredholographic pattern for each voxel or group of voxels is driven ontodisplay 110 and the exit signal 143 for that voxel is captured byimaging module 160 as an infrared image. Changes to that infrared imagefor that voxel indicate a change in the voxel or group of voxels.Imaging system 100 cycles through imaging each voxel or group of voxelsuntil each voxel or group of voxels of interest has been scanned. Athree-dimensional composite image can be generated by combining theimaged changes of each individual voxel over time. It is noted that oncea lookup table is generated that links each voxel or group of voxels toa preferred holographic pattern, using directional ultrasonic emitter115 or training stimuli are not required to perform the imaging ofdiffuse medium 130. Furthermore, imaging module 160 doesn't necessarilyneed to capture the phase of exit signals 143 since the pixel-by-pixelamplitude data for exit signal 143 may be sufficient for detection ofchanges in voxels.

The changing exit signals 143 for each voxel can show changes over time.Red blood cells are naturally occurring chromophores in that theiroptical properties correspond to whether the red blood cell is carryingoxygen or not. An oxygen depleted red blood cell will exhibit differentoptical properties than an oxygen rich red blood cell. Hence, exitsignal 143 for each voxel or group of voxels will change based on thelevel of oxygen in the red blood cells in that voxel. Oxygen consumptionin red blood cells corresponds to active areas of the brain. Thus, theactive areas of the brain can be known by analyzing the changes in exitsignals 143. The active areas in a brain may indicate an injury,inflammation, a growth, a specific thought, or a specific image thatsomeone is recalling, for example. A large change (over time) of exitsignals 143 in neighboring voxels could indicate a tumor growth, forexample. Additionally, detecting the active areas in particular voxelscan be mapped to different actions or thoughts that a person is having,as shown by Dr. Adam T. Eggebrecht of Washington University's School ofMedicine in St. Louis, Mo. Dr. Eggebrecht and his co-authors used a Timeof Flight measuring optical wig to map brain function in a May 18, 2014article in Nature Photonics entitled, “Mapping distributed brainfunction and networks with diffuse optical tomography.” This system candetect changes in other chromophores like lipid, melanin, water, andfat, but also directly detect changes in neurons themselves. Activeneurons change their light scattering properties through change inmembrane potential (a fast transition) or cell swelling (a slowtransition). Other optical changes in the body, either via chromophore,scattering changes or phase changes can be detected with this system.With the introduction of fluorescent dyes and particles opticalexcitation of areas that selectively uptake the wavelength shiftingmaterial can be detected by looking for the color shift. All of thesebeacon indicators can be used with the technique described.

FIG. 9 illustrates an example process 900 of linking a holographicpattern to a location of a diffuse medium that may be performed byimaging system 100 for example, in accordance with embodiments of thedisclosure. The order in which some or all of the process blocks appearin process 900 should not be deemed limiting. Rather, one of ordinaryskill in the art having the benefit of the present disclosure willunderstand that some of the process blocks may be executed in a varietyof orders not illustrated, or even in parallel. The instructions forprocess 900 may be stored in or accessible to processing logic 101 forexecuting, for example.

In process block 905, an ultrasonic signal (e.g. ultrasonic signal 117)is focused to a location in a diffuse medium (e.g. diffuse medium 130).A plurality of infrared imaging signals is directed into the diffusemedium by driving a corresponding plurality of holographic patterns ontoa pixel array (e.g. display 113), in process block 910. The plurality ofinfrared imaging signals is directed into the diffuse medium while theultrasonic signal is focused on the location. The plurality of infraredimaging signals (e.g. signal 123) may be directed into the diffusemedium by a holographic display such as display 110.

In process block 915, a plurality of images is captured. The images maybe captured by imaging module 160, for example. Each of the images inthe plurality captures a corresponding transmission of the plurality ofinfrared imaging signals directed into the diffuse medium. In otherwords, a first image in the plurality of images would capture a firsttransmission of a first infrared imaging signal generated by a firstholographic pattern being driven onto the pixel array, a second image inthe plurality of images would capture a second transmission of a secondinfrared imaging signal generated by a second holographic pattern beingdriven onto the pixel array subsequent to the first holographic patternbeing driven onto the pixel array, and so on. As described above,capturing a transmission (e.g. exit signal 143) of an infrared imagingsignal while an ultrasonic signal is focused on a voxel allows imagingsystem 100 to determine which holographic pattern is best suited toimage the voxel.

A selected image is determined from the plurality of images by analyzingthe plurality of images in process block 920. Each of the plurality ofimages has a corresponding holographic image pattern. In one embodiment,a phase component of each of the plurality of images is compared to aphase component of a unattentuated image that captured the transmissionof an infrared signal generated by the corresponding holographic imagepattern when the directional ultrasonic emitter was deactivated. In thisway, the phase difference of exit signal 143 can be detected for whenthe ultrasonic signal is and is not focused on a voxel of a diffusemedium. The analysis of process block 920 may further includedetermining the selected image by which of the plurality of images hadthe greatest phase change from its unattentuated image that was capturedwithout the ultrasonic signal 117 being focused on the location.

In process block 925, the holographic pattern that generated theselected image is identified as a preferred holographic pattern andlinked to the location. The location and holographic pattern may bestored in a lookup table so that the holographic pattern can be used toimage the linked location at a subsequent time.

Process block 925 may be repeated for each voxel of a diffuse mediumuntil each voxel of interest has been linked to a preferred holographicpattern that can be used to generate an infrared holographic imagingsignal for imaging the voxel.

Methods that don't use an ultrasonic signal may also be utilized to linka holographic pattern to a location of a diffuse medium. In oneembodiment, contrast enhancing injectables or other beacons (e.g. probe)are used to define a certain voxel. Chromophores themselves can also beused as beacons.

FIG. 11 illustrates an example process 1100 of linking a holographicpattern to a location of a diffuse medium, in accordance withembodiments of the disclosure. Process 1100 may be performed by system180 or by systems 100 or 200, where directional ultrasonic emitter 115is optional since process 1100 does not require directional ultrasonicemitter 115. The order in which some or all of the process blocks appearin process 1100 should not be deemed limiting. Rather, one of ordinaryskill in the art having the benefit of the present disclosure willunderstand that some of the process blocks may be executed in a varietyof orders not illustrated, or even in parallel. The instructions forprocess 1100 may be stored in or accessible to processing logic 101/201for executing, for example.

A plurality of infrared imaging signals 1101 is directed into thediffuse medium by driving a corresponding plurality of holographicpatterns onto a pixel array (e.g. display 113), in process block 1105.The plurality of infrared imaging signals (e.g. signal 123) may bedirected into the diffuse medium by a holographic display such asdisplay 110.

In process block 1110, a plurality of images 1102 is captured. Theimages 1102 may be captured by imaging module 160, for example. Each ofthe images in the plurality of images 1102 captures a correspondingtransmission of the plurality of infrared imaging signals 1101 directedinto the diffuse medium in process block 1105. In other words, a firstimage in the plurality of images 1102 would capture a first transmissionof a first infrared imaging signal generated by a first holographicpattern being driven onto the pixel array, a second image in theplurality of images would capture a second transmission of a secondinfrared imaging signal generated by a second holographic pattern beingdriven onto the pixel array subsequent to the first holographic patternbeing driven onto the pixel array, and so on. As described above,capturing a transmission (e.g. exit signal 143) of an infrared imagingsignal while a stimulus is first not present and then present allowsimaging system 100 to determine which holographic pattern is best suitedto image the group of voxels changed by the stimulus.

In process block 1115 a stimulus is introduced or a period of time isallowed to pass. Where the brain is being imaged, the stimulus (e.g.stimulus 197) may be showing an image to a person, playing music for theperson, or requesting that the person think of an idea or an image. Atprocess block 1120, the plurality of infrared imaging signals 1101 aredirected into the diffuse medium. In process block 1125, a plurality ofimages 1103 are captured. Each of the images in the plurality of images1103 captures a corresponding transmission of the plurality of infraredimaging signals 1101 directed into the diffuse medium in process block1120 while the stimulus of process block 115 is applied or presented.

In process block 1130, corresponding images from the plurality of images1102 and the plurality of images 1103 are compared to find the maximumdifferential between corresponding images. Corresponding images from theplurality of images 1102 and 1103 are images that are captured when thesame holographic pattern is driven onto the display. Each of theplurality of images has a corresponding holographic image patternwithout stimulus applied in the group of images 1102 and with stimulusapplied in the group of images 1103. In one embodiment, a phasecomponent of each image from 1103 is compared to a phase component of acorresponding unattentuated image from 1102 that captured thetransmission of an infrared signal generated by the correspondingholographic image pattern when no stimulus was presented. In this way,the phase difference of exit signal 143 for a given voxel can bedetected for when a stimulus is and is not present. The analysis findingthe maximum differential of process block 1130 may further includedetermining which of the corresponding images from 1102 and 1103 havethe largest phase change.

In process block 1135, the holographic pattern that generated themaximum differential in process block 1130 is identified as a preferredholographic pattern and linked to the location/voxel of interest. Thelocation and holographic pattern may be stored in a lookup table so thatthe holographic pattern can be used to image the linked location at asubsequent time.

Process block 1130 may be repeated for each stimulus of a diffuse mediumuntil the stimulus of interest has been linked to a preferredholographic pattern that can be used to generate an infrared holographicimaging signal for imaging the voxel.

FIG. 2 illustrates an imaging system 200 that includes an integratedmodule 290A that includes image pixel array 170, filter 173, IR director103, IR emitter 105, IR display 113, IR director 253, and IR emitter155. Imaging system 200 also include directional ultrasonic emitter 115and processing logic 201. Imaging system 200 may also include thewireless transceiver described in system 100 as coupled to processinglogic 201. In the illustrated embodiment of integrated module 290A,filter 173 is disposed between IR director 103 and image pixel array170. IR director 103 is disposed between IR display 113 and filter 173.IR display 113 is disposed between IR director 253 and IR director 103.

Imaging system 200 has similarities to imaging system 100. IR emitter105 is activated by output X3 of processing logic 201. IR director 103receives the infrared light from IR emitter 105 and directs the infraredlight to IR display 113 as IR wavefront 107 to illuminate IR display113. A holographic pattern is driven onto IR display 113 to generate aninfrared holographic imaging signal 223, which is directed to voxel 133.Signal 223 propagates through voxel 133 and is incident on integratedmodule 290B as exit signal 273. Integrated module 290B may be the sameas integrated module 290A, in FIG. 2. Integrated module 290B includes animage pixel array 170 that images exit signal 273 through IR display113. The amplitude and phase modulations (if any) of the pixels of IRdisplay 113 within integrated module 290B can be subtracted from theimage capture of exit signal 273 by processing logic 201 to determinethe actual image of exit signal 273. For example, if a display pixel ofIR display 113 within integrated module 290 was driven to cut theamplitude of incident infrared light in half, the image signal generatedby exit signal 273 on the image pixel directly behind the display pixelwould be multiplied by two to recover the original amplitude of exitsignal 273. In one embodiment, the pixel dimensions of display 113 andimage pixel array 170 are the same. The phase of the light from the exitsignal 273 can be recovered similarly by accounting for the phase shift(if any) that is driven onto display pixels of display 113.

Holographic patterns for driving onto IR display 113 to image differentvoxels of diffuse medium 130 may be determined similarly to process 900or 1100. Integrating IR display 113 with the image pixel array 170 inintegrated module 290 is potentially advantageous for packaging and formfactor reasons, as will be described in connection with FIGS. 4A and 5.Integrated module 290 may also be advantageous because integrated module290B could both image exit signal 273 and generate its own infraredholographic imaging signal 293 to be sent back to integrated module 290A(as exit signal 243) via voxel 133. In one embodiment, integrated module290B images exit signal 273 and determines the phase and amplitude ofthe exit signal 273 using the techniques described above. Since theoptical path between integrated modules 290A and 290B is reversible,integrated module 290B may calculate the conjugate of the imaged exitsignal 273 and drive the conjugate holographic pattern onto its own IRdisplay 113 to generate its own infrared holographic imaging signal 293that is directed back to IR display 113 via voxel 133 as exit signal243. As the infrared holographic imaging signal 293 propagates throughdiffuse medium 130 in the opposite direction, the phase and amplitudewill then match the initial holographic pattern driven onto IR display113 of integrated module 290A. The image pixel array 170 of integratedmodule 290A can measure the amplitude and phase of exit signal 243 andcompare it to the holographic pattern that was originally driven onto IRdisplay 113. Differences between exit signal 243 and the holographicpattern driven onto IR display 113 can then be detected and analyzed forchanges within voxel 133.

Although there will be some movement of the body when system 100 or 200is imaging, valuable imaging signals can still be obtained since themovement is relatively slow compared to the imaging speed. Movement ofthe tissue being imaged may come from movement of the head or from aheart pumping blood, or a vein expanding and contracting due todifferent blood flow, for example. To aid in the imaging, the MemoryEffect principles described in Issac Freund's 1988 article entitled,“Memory Effects in Propagation of Optical Waves through DisorderedMedia” (Rev. Lett 61, 2328, Published Nov. 14, 1988) can be employed.Additionally, big data analytics may be employed to organize the imagesof voxels into a composite image.

FIG. 3 illustrates an example placement of components of an imagingsystem 300 in relationship to a human head, in accordance with anembodiment of the disclosure. FIG. 3 is a top-down view of a human head305. Imaging system 300 includes display 110A-110D, imaging modules160A-160F, and directional ultrasonic emitters 115A and 115B. Components110A-110D and 160A-160F may all be replaced with module(s) 290 which canfunction as both display 110 and imaging module 160. Displays 110A-110Dand imaging modules 160A-F are shown in FIG. 3 although more or lessdisplays and imaging modules may be used in a system. FIG. 3 shows thatdisplay 110A may generate multiple holographic infrared imaging signals323 that are directed to image different voxels 333 of the brain whilethe exit signals 343 are imaged by different imaging modules 160. FIG. 3illustrates that display 110A sends an infrared holographic imagingsignal to each of imaging modules 160A-F. Not all the voxels, infraredholographic imaging signals, and exit signals are illustrated andreferenced in FIG. 3 as to not obscure the description of the system.The other displays 110B-110D may also send infrared holographic imagingsignals (not illustrated) to each of imaging modules 160A-F. Scientificliterature suggests that the penetration depth of infrared light intotissue is around 10 cm so multiple holographic displays 110 and imagingmodule 160 may be needed to image the entire brain or other tissue. Itis understood that multiple integrated modules 290 could also bestrategically placed around head 305 to image head 305.

FIGS. 4A and 4B illustrate example form-factor implementations of awearable imaging system, in accordance with an embodiment of thedisclosure. FIG. 4A includes a wearable imaging system 498 that includesfour optional directional ultrasonic emitters 115, five integratedmodules 290, and processing logic 401. Processing logic 401 may beimplemented similarly to processing logic 101. Wearable imaging system498 may include a fabric that has the illustrated components embeddedinto the fabric. The fabric may be in the form of a wrap that can bewrapped around an abdomen or other body area to facilitate imaging thosebody areas. The fabric may have velcro or other linking mechanism onedges to assist in maintaining a wrapping around a body area.

FIG. 4B includes a wearable imaging system 499 that includes twooptional directional ultrasonic emitters, six displays 110, six imagingmodules 160, and processing logic 402. Processing logic 402 may beimplemented similarly to processing logic 101. Wearable imaging system499 may include a fabric that has the illustrated components embeddedinto the fabric. The fabric may be in the form of a wrap that can bewrapped around an abdomen or other body area to facilitate imaging thosebody areas. The fabric may have velcro or other linking mechanism onedges to assist in maintaining a wrapping around a body area.

FIG. 5 illustrates an example configuration of a flexible wearableimaging system 599, in accordance with an embodiment of the disclosure.Imaging system 599 includes four optional directional ultrasonicemitters, one monolithic integrated module 290, and processing logic501. Processing logic 501 may be implemented similarly to processinglogic 101. Wearable imaging system 599 may include a fabric that has theillustrated components embedded into the fabric. The fabric may be inthe form of a wrap that can be wrapped around an abdomen or other bodyarea to facilitate imaging those body areas. The fabric may have velcroor other linking mechanism on edges to assist in maintain a wrappingaround a body area. Imaging system 599 is similar to imaging system 498in that it includes integrated modules. Integrated module 590 is similarto integrated module 290 except that integrated module 590 is built withflexible components so that integrated module 590 can be monolithic andtherefore provide a large-area holographic display and large-areaimaging module in one component that would be potentially less expensiveto manufacture. Flexible LCD technology is used for the holographicdisplay for example. It is understood that batteries, power regulators,and other required components of imaging systems 498, 499, and 599 arenot illustrated so as not to obscure the Figures of the disclosure.

FIG. 6 illustrates a networked system 600 in communication with anexample wearable imaging system for being worn on or about a head, inaccordance with an embodiment of the disclosure. System 600 includes aski-cap wearable 603 that is being worn on the head of a user. Systems100, 200, 300, 498, 499, and/or 599 may be included in wearable 603.Wearable 603 includes wired or wireless network connections to router615 and/or mobile device 612 (e.g. smartphone or tablet). Thecommunication channel 626 between wearable 603 and mobile device 612 maybe BlueTooth™ or WiFi utilizing IEEE 802.11 protocols, for example. Thecommunication channel 627 between wearable 603 and router 615 may use awired Ethernet connection or WiFi utilizing IEEE 802.11 protocols, forexample. Mobile device 612 may also communicate with wearable 603 viacommunication channels 628 and communication channel 627. Mobile device612 may give the users some results or alerts about the imaging beingperformed by wearable 603. Router 615 may also route data from wearable603 to a computer 611 via communication channel 629. Computer 611 mayfunction as a server, in some embodiments. Computer 611 may give medicalprofessionals access to the imaging of the user's brain by wearable 603,for example.

In one embodiment, processing intensive algorithms are performed bycomputer or server 611. For example, process 900 or 1100, imageprocessing algorithms, and simulated annealing algorithms describedabove may be performed by computer 611. In this case, the imagingmodules of the systems may capture the images and send the raw data tocomputer 611 for further processing. Computer 611 may then report theresults of the processing back to wearable 603 for local storage. Mobiledevice 612 may perform similar “off-site” processing for wearable 603.

The techniques described in this disclosure have been described largelyin the context of medical imaging. However, the uses of the methods,systems, and devices are not so limited. In one embodiment, imagingsmall voxels of the brain is used as a way to discern thoughts.Different thoughts and images correspond to different blood usage byneurons (as shown by Dr. Eggebrecht and his co-authors, and others)which can be imaged by the systems, devices, and methods describedherein. Discerning (even rudimentary) human thought can be used toassist quadriplegics and others who don't have full functionality oftheir extremities. Imaging their thoughts could allow for translatingtheir thoughts into a mechanical action (e.g. driving a wheelchairforward or typing words). In one implementation, a user recalls (thinksabout) an image of a forward arrow. Imaging system 100, 200 or 280images the brain and records a voxel pattern that is known to be linkedto the forward arrow recalled by the user. When imaging system 100, 200,or 280 images the forward arrow thought pattern, it generates anadditional action (e.g. rolling wheel chair forward or typing an “uparrow” on a keyboard).

In one use contemplated by the disclosure, sending infrared light tospecific voxels of the brain is used as a therapy. In some cancertreatments, binding agents are ingested or injected, where the bindingagents are targeted to selectively bind to tumors. Once the bindingagents are bound to the tumor, the described systems could activate thebinding agent by selectively exciting the binding agent with infraredlight (on a voxel-by-voxel basis), for example. In another usecontemplated by the disclosure, the described systems are used in thefield of optogenetics—to change the state of neurons with light therapy.Changing the state of neurons with light therapy allows for stimulationof areas of the brain that may otherwise require a physical fiber opticprobe being inserted. Light therapy can be used for treatment andresearch for autism, Schizophrenia, drug abuse, anxiety, and depression,for example. Changing the state of neurons with light therapy may alsoallow for images or other information to be imparted to the brain, whichmay be especially useful for patients with memory loss.

The processes explained above are described in terms of computersoftware and hardware. The techniques described may constitutemachine-executable instructions embodied within a tangible ornon-transitory machine (e.g., computer) readable storage medium, thatwhen executed by a machine will cause the machine to perform theoperations described. Additionally, the processes may be embodied withinhardware, such as an application specific integrated circuit (“ASIC”) orotherwise.

A tangible non-transitory machine-readable storage medium includes anymechanism that provides (i.e., stores) information in a form accessibleby a machine (e.g., a computer, network device, personal digitalassistant, manufacturing tool, any device with a set of one or moreprocessors, etc.). For example, a machine-readable storage mediumincludes recordable/non-recordable media (e.g., read only memory (ROM),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, etc.).

The above description of illustrated embodiments of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various modifications arepossible within the scope of the invention, as those skilled in therelevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific embodimentsdisclosed in the specification. Rather, the scope of the invention is tobe determined entirely by the following claims, which are to beconstrued in accordance with established doctrines of claiminterpretation.

What is claimed is:
 1. A medical imaging device comprising: processinglogic; an emitter for emitting infrared light within a frequency band; adisplay pixel array including a plurality of pixels, each pixel in theplurality of pixels is individually configurable to modulate anamplitude of the infrared light received from the emitter to generate aninfrared holographic imaging signal according to a holographic patterndriven onto the display pixel array by the processing logic; and animage pixel array including a plurality of imaging pixels configured toreceive incident light within the frequency band and reject lightoutside of the frequency band, the processing logic coupled to the imagepixel array to initiate a capture of an infrared image, wherein theprocessing logic is further coupled to receive the captured infraredimage from the image pixel array.
 2. The medical imaging device of claim1 further comprising: a reference wavefront generator configured toilluminate the image pixel array with a reference wavefront in responseto receiving an activation signal generated by the processing logic, theprocessing logic causing the reference wavefront generator to illuminatethe image pixel array during a time period overlapping with thecapturing of the infrared image by the image pixel array, wherein thereference wavefront is within the frequency band.
 3. The medical imagingdevice of claim 2, wherein the reference wavefront generator receivesthe infrared light from the emitter, and wherein the emitter is a laserand the frequency band is monochromatic infrared light.
 4. The medicalimaging device of claim 1 further comprising: a directional ultrasonicemitter configured to dynamically focus an ultrasonic signal to a givenvoxel in three-dimensional space, wherein the processing logic isconfigured to drive the directional ultrasonic emitter to focus theultrasonic signal to a first voxel in three-dimensional space while alsodriving the holographic pattern onto the display pixel array and whileinitiating the capture of the infrared image with the image pixel array.5. The medical imaging device of claim 1, wherein the image pixel arrayis positioned to image an exit signal generated by the infraredholographic imaging signal propagating through a diffuse medium.
 6. Themedical imaging device of claim 1, wherein the incident light receivedby the image pixel array passes through the display pixel array beforebeing incident on the image pixel array.
 7. The medical imaging deviceof claim 1, wherein a pixel pitch of the display pixel array is lessthan or equal to five times the wavelength of the monochromatic infraredlight.
 8. The medical imaging device of claim 1, wherein the displaypixel array is included in a holographic display and each pixel in thedisplay pixel array is independently configurable to modulate a phase ofthe infrared light received from the emitter.
 9. The medical imagingdevice of claim 8, wherein modulating the phase of the infrared lightfor each of the pixels in the plurality of pixels includes driving avoltage across two electrodes of the pixel to align liquid crystalbetween the two electrodes to change a length of an optical path of theinfrared light propagating through the pixel in order to achieve aspecified phase of the infrared light as it exits the pixel.
 10. Amethod of imaging tissue, the method comprising: illuminating a displaypixel array with an infrared wavefront within a frequency band; formingan infrared holographic imaging signal by driving a holographic patternonto the display pixel array while the display pixel array isilluminated by the infrared wavefront; capturing an infrared image bymeasuring the amplitude of an exit signal with pixels of an image pixelarray, the exit signal generated by the infrared holographic imagingsignal propagating in the tissue, wherein the pixels of the image pixelarray are configured to receive light within the frequency band andreject light outside the frequency band; and generating a compostieimage of the tissue, wherein the composite image includes the infraredimage captured by the image pixel array and additional infrared imagescaptured by the image pixel array while corresponding additionalholographic patterns are driven onto the display pixel array.
 11. Themethod of claim 10 further comprising: directing a reference wavefrontto the image pixel array and capturing the infrared image while thereference wavefront is incident on the image pixel array; andcalculating a phase of the exit signal.
 12. The method of claim 10,wherein the holographic pattern is configured to direct the infraredholographic imaging signal to the image pixel array via propagationthrough a voxel in the tissue, wherein the holographic pattern is linkedto the voxel.
 13. The method of claim 12 further comprising: determininga difference between the infrared image and a prior infrared image thatwas captured by the image pixel array while the holographic pattern wasdriven onto the display pixel array during a past time period.
 14. Themethod of claim 12 further comprising: selecting a second holographicpattern associated with a second voxel; forming a second infraredholographic imaging signal by driving the second holographic patternonto the display pixel array; and capturing a second infrared image bymeasuring a second exit signals with the image pixel array, wherein thesecond exit signal is generated by the second infrared holographicimaging signal propagating through the second voxel in the tissue. 15.The method of claim 10, wherein a pixel pitch of the display pixel arrayis less than or equal to five times the wavelength of the infraredwavefront.
 16. A method comprising: focusing an ultrasonic signal to alocation in tissue; directing a plurality of infrared imaging signalsinto the tissue by driving a corresponding plurality of holographicpatterns onto a pixel array, the plurality of infrared imaging signalsdirected into the tissue while the ultrasonic signal is focused on thelocation; capturing a plurality of images, wherein each of the pluralityof images captures a corresponding transmission of the plurality ofinfrared imaging signals directed into the tissue while the ultrasonicsignal is focused on the location; selecting a preferred holographicpattern from the plurality of holographic patterns; and generating acomposite image of the tissue, wherein generating the composite image ofthe tissue includes driving the preferred holographic pattern onto thepixel array when the ultrasonic signal is not focused on the location inthe tissue.
 17. The method of claim 16, wherein focusing the ultrasonicsignal includes: directing an ultrasonic signal to a membrane; anddriving an electronic signal to the membrane to shape the membrane tofocus the ultrasonic signal to the location.
 18. The method of claim 16further comprising: linking, in a computer-readable medium, thepreferred holographic pattern to the location.